冲绳海槽中部Jade热液区热液沉积物中Ag的富集成矿作用

冲绳海槽Jade热液活动区热液沉积物主要以块状硫化物和硫酸盐矿物为主。与其它热液活动区相比,本区的热液沉积物以富含Pb和Ag等元素为特征。电子探针和中子活化的分析结果表明,在块状硫化物矿石中,Ag主要以分散态富集在粗粒硫化物和细粒硫化物集合体中,在热液活动的早期和晚期均有Ag的富集。在以硬石膏为主的块状矿石中,Ag主要在细粒硫化物集合体中富集,其富集成矿的时间为热液活动的中后期,富集成矿温度在150℃以上。在重晶石为主的块状矿石中,Ag主要以颗粒状自然银的形式在热液活动后期富集成矿,其成矿温度低于160℃。

Silver Enrichment and Mineralization of Seafloor Hydrothermal Sediment from the Jade Hydrothermal Field in the Middle Okinawa Trough

The hydrothermal sediments from Jade hydrothermal field are mainly composed of massive sulfide ore and massive sulfate ore. The massive sulfide ore is characterized as the richness of Pb and Ag. According to electron microprobe analysis and neutron activation analysis, silver is mainly rich in the coarse grained sulfide and fine grained sulfide aggregate as dispersion regime in the massive sulfide ore. Silver enrichment mineralization occurs in the early and late period of hydrothermal activity. In the massive sulfate ores mainly composed of anhydrite, silver is rich in the fine grained sulfide aggregate at dispersion regime. Silver is rich at above 150 degree centigrade in the middle late period of hydrothermal activity. Natural silver is found in sulfate ores mainly composed of barite for the first time, which is the major regime of concentration for silver. Silver enrichment mineralization occurs at below 160 degree centigrade in the late period of hydrothermal activity.